With the advances of microprocessor and communication technologies, mobile communication has played an important role in modern consumer market. Typical mobile devices may pack many advanced features such as high resolution graphics and imaging, voice processing, and intelligent user's interface in compact and low power handsets. One problem with modern mobile devices is the control of call initiation, such as unintended outgoing calls. For example, when a mobile handset is placed in a user's pocket, handbag, or purse, unintended or accidental call initiation may occur when the device input entry (e.g., keypad) is accidentally pressed due to pressure or movement. Such an unintended outgoing call may create several problems including incurring costs due to long running message left to voicemail of the recipient, compromising privacy or personal security.
Existing techniques to overcome the above problems have a number of drawbacks. One technique is to use a locking mechanism to lock the call functionality when the device is not in use. The locking mechanism may be a physical lock (e.g., a switch) or a soft key lock in which the user enters a keystroke or a sequence of keystrokes. This technique requires a conscious user action and may be inconvenient. In addition, if the device is Bluetooth-enabled, it may be activated even while being locked. Another technique monitors the outgoing and incoming voice levels to detect an absence of conversation in both directions and activates an alarm if an absence of such conversation is detected. This technique may not be fool-proof because the noise environment at the calling device, such as loud background music, may be such that the outgoing voice levels may be erroneously interpreted as an intended voice communication.